Saskatchewan hockey player Mandi Schwartz has lost her valiant battle with leukemia.

Thousands of people rallied to her side to help her in that battle, but the 23-year-old from Wilcox, Sask., died Sunday after two years of fighting the disease, according to her high school Notre Dame College.

She went into a Regina hospital on Saturday night and died Sunday morning, said Notre Dame College president Rob Palmarin.

"We're all a bit taken aback and saddened because she's one of ours," Palmarin told The Canadian Press. "Mandi's struggle with leukemia was particularly close to everyone's heart here. For the last couple of years, we've been praying for her at assemblies and held a couple of fundraisers to help with her family's costs when they travelled to the States for treatment."

Schwartz played forward for the Yale Bulldogs and also attended Canadian women's team camps. Before heading to Yale, she played girls' hockey for the Notre Dame Hounds in Wilcox and graduated in 2006.

Schwartz's brothers Jaden and Rylan play hockey for Colorado College in the NCAA and are also Notre Dame alumni.

The Schwartz family fought hard for her survival. Her father Rick and mother Carol took leave from their jobs with the Saskatchewan Safety Council and Saskatchewan Justice respectively to shepherd their daughter through treatment.

She was engaged to engineering student Kaylem Prefontaine of Rockglen, Sask., and they had planned a wedding for the summer of 2012.

She was first diagnosed with acute myeloid leukemia in 2008 during her junior year at Yale. AML is an aggressive cancer of the blood and bone marrow.

Chemotherapy sent her into remission and she returned to Yale, but Schwartz suffered a relapse in April, 2009. Schwartz's situation was dire and she desperately needed a stem cell transplant.

Yale and other hockey communities in North America combined to launch a massive on-line campaign searching for both bone marrow matches and umbilical cord blood from women about to give birth. The Facebook page "Become Mandi's Hero" drew almost 6,500 followers at the campaign's peak.

Donors were found, but Schwartz's transplant scheduled for Aug. 26 was delayed when it was discovered the cancer had again returned.

She had more chemotherapy in Seattle before stem cells from two umbilical-cord donors were transplanted Sept. 20 at the University of Washington Medical Center.

Schwartz and her parents remained in Seattle for weeks for follow-up treatment. They hoped the transplant would do its job. Schwartz went home to Wilcox, but tests in late December revealed the devastating news that her cancer had returned.

Her younger brother Jaden was drafted 14th overall by the NHL's St. Louis Blues last year and played for Canada at this year's world junior championship in Buffalo, N.Y.

"From the entire St. Louis Blues organization, our thoughts and prayers are with the Schwartz family during this difficult time," Blues president John Davidson said Sunday in a statement.

Mandi was part of Jaden's welcoming party at the Regina airport Jan. 6 upon his return from the world junior championship in Buffalo.

A fractured ankle suffered during the tournament prevented Jaden from playing for Canada in the medal round. He greeted his sister on crutches and draped his silver medal around her neck.

Her family wrote in a CaringBridge on-line posting that day that bone marrow tests revealed leukemia had aggressively settled in her bones. The treatment they'd hoped to continue in Saskatchewan was not possible.

"The one thing about Mandi is she had a relentless spirit, a never-give-up attitude and she had a plan and vision for her life," Palmarin said. "As she was battling this cancer, the big miracle was how she really rubbed off on other people, that here's this girl with such strong hope and belief.

"She was an inspiration to a lot of our students and staff because of that attitude towards life. Right now it's tough because we mourn not only for Mandi but for her family and her fiancee."